Bora-Care And Shell-Guard Wood Treatments

Bora-Care & Shell-Guard Wood Preservatives

- Borate & glycol-based wood treatments -

Summary: Bora-Care and Shell-Guard are borate-based liquid wood preservatives used to protect wood against wood destroying insects and dry rot fungi.

Bora-Care & Shell-Guard

Bora-Care (Nisus Corporation) and Shell-Guard (Perma-Chink Systems) are borate-based wood treatments for the prevention of decay fungi and insect damage. Both products use glycol* to increase the penetration of the borate preservative into wood fibers.

As insecticide/fungicides both Bora-Care and Shell-Guard are labeled for use against termites, wood-destroying beetles, carpenter ants, and wood decay fungi (dry rot). Both are very effective against many of the most important wood destroying organisms and exhibit relatively low toxicity compared to other pesticides.

Common misspellings and common names: Boracare, Shellguard

*Bora Care contains ethylene glycol while Shell-Guard contains a less toxic form of glycol called propylene glycol.

Bora-Care and Shell-Guard are used to protect finished wood

Hardwood lumber; photo by Stephen Bratkovich, USDA Forest Service.

Using Bora-Care or Shell-Guard

Both Bora-Care and Shell-Guard are thick liquids that should be diluted with warm water prior to use. Most applications call for a 1:1 dilution. Bora-Care is 40% sodium borate while Shell-Guard is less concentrated at about 25%. Both can be applied with a garden sprayer, paint brush or paint roller but follow application instructions carefully.

The main advantages of products like Bora-Care and Shell-Guard, when compared to conventional pesticides, are: low toxicity, very long residual activity, highly effective, and low application costs. The main disadvantage is that because borates are water soluble they must be protected from excessive moisture with a water resistant finish when used in wet environments like the exterior of log homes.

Is the glycol (penetrant) really necessary?

Glycol-based borates like Bora-Care and Shell-Guard are somewhat more expensive than powdered borates like Tim-Bor (Tim-Bor does not use glycol; see Using Tim-Bor To Protect Wood). However, some studies have shown that the glycol component helps the borates penetrate deeper into wood fibers while other studies found no difference. The active ingredient in both is boric acid, borate is a salt of boric acid. Powdered borates like Tim-Bor can also be purchased in smaller quantities so for small jobs this may be the way to go.


Bora-Care and Tim-Bor: both are generally not available in retail stores but can be purchased here ( Shell-Guard is available through the manufacturer.

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